Say I found this domain "runescape.ws" free to register - should I do it or not legally wise? I mean, could the Jagex company take it from me or only if I would use the name of the actual company in the domain name? I also intend to make the site related to that game with forums/ tips, etc. Of course the above was just an example but it's with another game that's quickly becoming popular and I saw a few TLDs available for registration. Could I register these and then offer them for sale to the company or start building up the forums website myself (which are my intentions ideally) without getting any problems? Maybe the example I gave was too radical but would it still apply to a smaller community and a more recent game, say released in January?
Registering a domain name simply to offer to sell it to the company who owns the trademark is a quick way to get taken out behind the wood-shed and beaten. Technically extortion, they will probably attempt to take control over the domain. There are some fair use provisions, as long as you don't try to knock off the game or attempt to defraud the company or it's users you probably won't have any trouble. Just from personal experience though, Runescape Forums are super difficult to start.
Yeah, I don't want to sell it to the company or do any kind of extortions - I simply want to start a site related to the game and rank it amongst the first for that name keyword on Google. I don't know whether to buy a domain with only the game name in it OR the game name and another related word OR something different from the game name so I don't have any problems. There, I rephrased the question!
No idea about Jagex, but for example a big company like NCSoft has no problems if the fansites use other domain extensions for there game fansites.
The company will definitely take action if the name is trademarked and if people could mistakenly associate your site with the company. If the site was not related to runescape at all then you would stand a good chance in a domain dispute. However with your plans it's very likely you'll get into trouble and that they'll take the domain away from you.